LED Brightness upgrade calulator (excel)

**Fusion-One** · 11-17-2005, 08:02 PM

I've been curious about using super bright LED's as a possible brightness enhancement.. They're very efficient when it comes to lumens/watt, last forever, and are fairly easy to source (ebay!

) I learned pretty quickly that the MCD rating isn't very useful until you twist it around a bit.. so I made up this calculator in excel. Enter in your LED's Properties, screen dimensions, and itll give you the info you need to see if it'll work. (most importantly the cd/m²).. it also gives a percentage of how visible the LED array would be against 100% direct sunlight. Something it doesn't take into consideration is touchscreen overlays and the screen's gain... however, it gives a good start.

These LED's on ebay would do the trick... 10mm LED's are too weak all around.. and 3mm LED's are insane for the light output theyd give... but would be pretty impossible to setup.

Defaults in the excel sheet are based on these LED's and 7" tft dimensions.

Feedback, and double checking my equations is appreciated.

**xdjxklusivex** · 11-17-2005, 09:39 PM

it would be too expensive ive got white 5mm 50000 mcd leds and those r liek 3 bucks a pop! but my god r they bright... the only thing u will have to think about is that oon the screen its gonna have dots because its so close and leds r like directional and kinda project the light

**Fusion-One** · 11-17-2005, 10:59 PM

50000mcd? Whats the projection angle on those? The link I posted, doing a complete upgrade on a 7" tft would be about 225$ shipped, and its always cheaper to buy bulk, especially with electronics components. I bet that vendor would offer a nice price break on a thousand of them.

20 degree projection from 5mm LEDs touching side to side on a panel with a light dispersion lens over it.. I honestly cannot see this causing hot spots :P

**xdjxklusivex** · 11-17-2005, 11:51 PM

225 just for the backlight upgrade??? daymmm lol

**Bugbyte** · 11-18-2005, 12:02 AM

Have you checked the backlight upgrade thread? They discussed doing it this way and discarded it for technical reasons. Might want to check on that before trying.

**viper24** · 11-18-2005, 12:10 AM

hey speaking of LEDs here, I am removing my overhead consoles lights to mound my A/C controls and am putting about 10-15 LEDs there, what should I get???

**Fusion-One** · 11-18-2005, 12:43 AM

I have read it in the past, but didn't want to tackle that beast-monster again to see and remember what it had to say.. :P We really need the feature of "Show all posts" in a thread, so that it can be string searched within the browser.

Filtering 20 degree beams spaced 5mm apart through a good frensel lens or two, I can't see there being any hotspot troubles.

Assuming 100% inefficiency, and 51w thermal energy loss, its still no problem to cool this, given that the surface area of the board would be 15cmx10cm.. a few copper fins soldered to the back of the board with the power traces, with a slow 120cm fan moving air over them would keep them cool... and thats assuming total inefficiency.. which LEDs are very far from.. even going with a safe figure of 50% efficiency.. thats only 25 watts of heat to disipate.

Of course, none of this will fit back into the housing.. but I don't see that really being a problem, considering most people dashmount anyways.

I'm just making educated estimates here, really.. but from my experience with overclocking.. 25watts is a walk in the park to get rid of.. the biggest thing I can really see would be mounting all of the LED's onto a PCB.. I think vero board would be ideal.. just a matter of going along with some solder and doing each leg one after another as you go down the row, connecting a row in parallel, and then connecting 4 rows in series to a 7812 to give 3 volts on each LED, and keeping the 7812's cool would be cake since youd only be taking 60% of their capacity... Theres definatly some work involved, but its straight forward and simple.

630 40000mcd 20 degree white LEDs - 199$
7 LM7812's - 6$
Veroboard - 4$
Solder - 5$
Copper sheet to cut fins from - no clue on cost, but I imagine cheap.. and if not, pennies to the rescue.

so, roughly 220$, and some time to get it going.

**Fusion-One** · 11-18-2005, 12:45 AM

Originally Posted by viper24

hey speaking of LEDs here, I am removing my overhead consoles lights to mound my A/C controls and am putting about 10-15 LEDs there, what should I get???

Be wary of super high rated mcd LED's.. make sure to check the projection angle.. using the little excel calc I put up, you can see roughly how many lumens you'll actually get out of the LED's.. just enter the angle and mcd rating.

For your purpose, the wider the angle you can find, the better.

**rudeboymcc** · 01-05-2006, 10:24 AM

surely the number of led's you're using is overkill? can you not just move the leds slightly further away from the lcd and use about half the number?

**jcdillin** · 01-05-2006, 11:17 AM

then your just going to end up with a backlighting system and not a backlight upgrade system.

The whole reason that this was discarded was mainly the price. It was going to cost way more to do a LED upgrade even with a buttload of standard LED's. The other way is turbocad's Luxeon upgrade, but then your looking at $1000.00 just to upgrade your screen. For that i'll pay someone else to do it.

The other reason was we were trying to make it all fit back into the standard casing, yes most people have their screens dash mounted, but that doesnt mean they have space behind it to fit a big array of LED's and fresnel lenses. But we almost had it fitting into a stock lilliput casing.